1. Field of the Invention
The present invention relates to a vehicular active vibrational noise control apparatus for canceling vibrational noise produced in a passenger compartment of a vehicle during traveling of the vehicle, using canceling vibrational noise that is emitted in the passenger compartment.
2. Description of the Related Art
Recently, there has been proposed an active vibrational noise control apparatus (hereinafter also referred to as an “ANC (Active Noise Control) apparatus”), which cancels vibrational noise produced in a passenger compartment of a vehicle during traveling of the vehicle, by emitting, from a speaker, a vibrational noise canceling sound that is in opposite phase to the vibrational noise, in combination with music sounds based on an audio signal.
Japanese Laid-Open Patent Publication No. 2009-045955 discloses an ANC apparatus, which is capable of compensating with high accuracy a reduction in quality of an audio sound based on an audio signal, by extracting a component around the frequency of road noise from the audio signal, and performing appropriate signal processing on the extracted component.
According to Japanese Laid-Open Patent Publication No. 2008-137636, there is proposed an ANC apparatus for adjusting the amplitude of a canceling signal based on the signal level of an audio signal (hereinafter also referred to as a “signal level”) or the vehicle speed of a vehicle that incorporates the apparatus therein. For example, according to Japanese Laid-Open Patent Publication No. 2008-137636, the amplitude of the canceling signal is adjusted to nil if a condition is satisfied, for example, in which the vehicle speed is zero or the audio signal level is greater than a predetermined value.